1. Technical Field
This invention relates to the procedure of amniocentesis and, in particular, relates to a needle for specific use in such procedure.
Amniocentesis is a procedure utilized to obtain 10 to 20 cc of amniotic fluid from a pregnant woman's uterus for diagnostic purposes. Such fluid is obtained, in the prior art, by inserting a long spinal needle, having a sharp-cutting tip, through the skin, fascia and uterine muscle into the uterine cavity and obtaining therefrom such amniotic fluid by aspiration. Complications, including trauma, hemorrhage and infection have resulted from employing such prior-art surgical needle in such procedure. Concomitantly, the fetus, umbilical cord or placenta may be punctured by such sharp-cutting surgical needle and with such resulting injuries that vary from scratching of parts of the fetus to intrauterine hemorrhage, causing fetal distress and intrauterine death. Fetal pneumothorax and cord hematomas have occurred.
Prior to this invention, there was no safe needle specifically designed for this procedure. The medical literature is replete with documented cases substantiating the prior-art problems, to wit: fetal bleeding and death from puncture of the umbilical cord; free flow of blood from needle puncture of the umbilical cord wrapped around the baby's neck with puncture of the nuchal cord; puncture through a vessel on the fetal surface of the placenta; thoracic puncture resulting in pneumothorax; laceration of the fetal spleen with rupture of the membranes; surgical emphysema and pneumothroax; puncture of the eye requiring its subsequent surgical removal; spontaneous abortion resulting from leakage of amniotic fluid; gangrene of fetal limb as a result of the subclavian artery being punctured; amputations of the fetal limbs within the mother's womb; blindness resulting from ocular puncture; puncture of the fetal peritoneal cavity causing ileal atresia and ileocutaneous fistula; obstruction of the small bowel; scars all over the fetal bodies from needle laceration and needle scratchings; laceration of the spleen, cardiac tamponade, subdural hematoma, arteriovenous fistula; rupture of fetal membranes; the complications of needle-tract endometriosis; respiratory difficulties, major orthopaedic deformities, premature ruptures of the membranes, hemorrhage; needle injury to the myocardium, lung, liver, spleen and brain; fetal exsanguination.
The problems with utilizing such spinal needle with its sharp-cutting tip are the potential and actual injuries to the fetus. This susceptibility for causing injuries arises from the fact that the needle must be manipulated and otherwise moved while in the uterus to obtain the required quantity of amniotic fluid along with some fetal debris for diagnostic purposes. The needle further must be appropriately manipulated and moved in the uterus to free the tip of the spinal needle from any clogging debris.
Accordingly, the object of the invention is to contribute to the solution of the discussed problems of the prior art by providing a safe amniocentesis needle specifically designed and constructed for such diagnostic procedure with the possibility of any injury to the fetus minimized and with any clogging of the needle likewise minimized.
The hollow needle of this invention is specifically designed and constructed to aspirate fluid with a maximum of suction but with a minimum of negative (suction) pressure. The four side holes within 1 cm of the needle tip minimize disturbance of the environment in the amniotic cavity and fetus. The five holes, i.e., the lumen of the hollow needle and four side holes cooperate to equalize suction. The external diameter of the hollow needle is kept to a minimum to minimize unnecessary trauma to the mother, her uterus and tissue. Tissue damage occurs in the prior art due to the larger puncture hole along with the leakage of fluid. Since the four side holes are within 1 cm of the needle tip, the sampling of amniotic fluid is uncontaminated because the effective aspiration area of the hollow needle is minimal. Hence, pure and uncontaminated amniotic fluid can be aspirated. In the prior art, contaminated fluid is drawn from the amniotic cavity when blood from the placenta or afterbirth blood from the mother's blood vessel or tissue is drawn. If such procedure is contaminated, then the procedure must be repeated with the risk of injury and trauma. The hollow needle has a blunt, round and non-cutting tip in order that it can be manipulated and otherwise moved while it is in the womb. Hence, needle injury to the fetus upon penetration or subsequent movement of the needle tip hardly presents a problem because any potential fetal injury is minimal.